Netcentric Fundamentals (ITT501) Chapter 1 PDF

Netcentric Fundamentals (ITT501) Chapter 1 - Introduction Topic Outline ▰ Background and history of ▰ Mobile and wireless networking and the computing internet ▰ Network Security ▰ Network Architecture and ▰ Networked multimedia Protocols...

Netcentric Fundamentals (ITT501) Chapter 1 - Introduction Topic Outline ▰ Background and history of ▰ Mobile and wireless networking and the computing internet ▰ Network Security ▰ Network Architecture and ▰ Networked multimedia Protocols system ▰ Client/Server paradigms ▰ Distributed Computing 2 Netcentric Computing ▰ CC2001 introduced a Knowledge Area (KA) entitled “Net-Centric Computing”, which encompassed a combination of topics including traditional networking, web development, and network security. ▰ range of sub-specialities including: ○ computer communication network concepts and protocols, multimedia systems, Web standards and technologies, network security, wireless and mobile computing, and distributed systems. 3 Netcentric Principle ▰ Net-Centric Computing (NCC) principle is based on a distributed environment where multiple components, possibly across geographical boundaries, that communicate and coordinate their actions through message passing. ▰ To an actor outside this system, it appears as if a single coherent system. ▰ Example : The Internet 4 The Internet 5 Background and history of networking and the internet 6 7 NETWORK ▰ Computer network is a collection of computing devices that are connected in various ways in order to communicate and share resources ▰ Usually, the connections between computers in a network are made using physical wires or cables ▰ However, some connections are wireless, using radio waves or infrared signals 8 NETWORK ▰ Computer networks have opened up an entire frontier in the world of computing called the client/server model 9 History of Network ▰ The Advanced Research Projects Agency Network (ARPANET) is one of the world's first packet switching networks, the first network to implement TCP/IP, and was the main progenitor of what was to become the global Internet. (later DARPA) ▰ ARBA network was initially funded by the Advanced Research Projects Agency (ARPA, later DARPA) within the U.S. Department of Defense for use by its projects at universities and research laboratories in the US. ▰ The packet switching of the ARPANET, together with TCP/IP, would form the backbone of how the Internet works. 10 Network and Internet History Timeline ▰ https://www.livescience.com/20727-internet-history.html ▰ https://www.ssl2buy.com/wiki/internet-history 11 INTERNET ▰ It is the largest network in the world that connects hundreds of thousands of individual networks all over the world. ▰ The popular term for the Internet is the “information highway”. ▰ Rather than moving through geographical space, it moves your ideas and information through cyberspace – the space of electronic movement of ideas and information 12 13 Internet Ownership ▰ No single person or company owns the Internet or even controls it entirely. As a wide-area network, it is made up of many smaller networks. These smaller networks are often owned and managed by a person or organization. The Internet, then, is really defined by how connections can be made between these networks. 14 World Wide Web (WWW) ▰ The Web (World Wide Web) consists of information organized into Web pages containing text and graphic images. ▰ It contains hypertext links, or highlighted keywords and images that lead to related information. ▰ A collection of linked Web pages that has a common theme or focus is called a Web site. 15 16 Network Architecture and Protocols 17 Network Architecture ▰ Understanding of the relationships between (architectural) components of the network. ▰ Network architecture guides the technical design of the network, through the application of high-level design principles to the network building blocks. ▰ The generic term node or host refers to any device on a network 18 Types of Network ▰ Local-area network (LAN) A network that connects a relatively small number of machines in a relatively close geographical area. ▰ Wide-area network (WAN) A network that connects two or more local-area networks over a potentially large geographic distance ▰ Metropolitan-area network (MAN) The communication infrastructures that have been developed in and around large cities ▰ Wireless Network 19 LAN Topologies(Physical) 1) Bus 2) Star 3) Ring 4) Switched 5) Daisy chains 6) Hierarchies 20 WAN Topologies 1) Peer-to-peer WANs 2) Ring WANs 3) Star WANs 4) Full-mesh WANs 5) Partial-mesh WANs 6) Two-tiered 7) Three-tiered 8) Hybrids 21 Connections ▰ Internet backbone A set of high-speed networks that carry Internet traffic ▰ Internet service provider (ISP) A company that provides other companies or individuals with access to the Internet 22 ▰ Internet: LANs, WANs, and individual devices connected via TCP/IP software ▰ Intranet: private net accessible to internal users ▰ Extranet: intranet extended to include some external users ▰ Virtual private network (VPN): uses public network as if it is private 23 Ports and Addresses ▰ Ports are destination points within a host computer. ▰ Processes are attached to the ports, enabling them to communicate. ▰ Transport layer addresses are composed of network address of the host computer and a port number. ▰ In the Internet every host is assigned a unique IP number which is used in routing. ▰ In an Ethernet each host is responsible for recognizing that the messages meant for it. 24 Protocols ▰ The term protocol refers to a well-known set of rules and formats to be used in order to perform a task. For example, a task of communicating between processes. ▰ Parts of a protocol: ○ A specification of a sequence of messages that must be exchanged. ○ A specification of the format of the data in the messages. ▰ Existence of well-known (standard) protocols enables the separate components of the distributed systems to be developed independently in different languages and on different platforms. 25 26 Client/Server paradigms 27 ▰ A simple definition of Client/Server is “ server software accepts requests for data from client software and returns the results to the client” 28 ▰ Servers ○ Run all the time (i.e. infinite) ○ Provide service to any client ○ Typically specialize in providing a certain type of service, e.g. Mail. ○ Listen to a well-known port and passively open connection. ▰ Clients ○ Run when needed, then terminate (i.e. finite) ○ Actively Open TCP or UDP connection with Server’s socket. 29 ▰ Client/server architecture has many variations based on tiers. ▰ tier architectures try to separate the components into different tiers/layers ○ Tier: physical separation ○ Layer: logical separation ▰ tier architectures have the same components o Presentation o Business/Logic o Data 30 Layers ▰ Presentation Layer ○ Static or dynamically generated content rendered by the browser (front-end) ▰ Logic Layer ○ A dynamic content processing and generation level application server, e.g., Java EE, ASP.NET, PHP, platform middleware ▰ Data Layer ○ A database, comprising both data sets and the database management system or RDBMS software that manages and provides access to the data (back-end) 31 1-Tier Architecture / Standalone ▰ All 3 layers are on the same machine o All code and processing kept on a single machine. sometimes access by dump terminal ▰ Presentation, Logic, Data layers are tightly connected o Scalability: Single processor means hard to increase volume of processing o Portability: Moving to a new machine may mean rewriting everything o Maintenance: Changing one layer requires changing other layers 32 2-Tier Architecture ▰ Database runs on Server o Separated from client o Easy to switch to a different database ▰ Presentation and logic layers still tightly connected (coupled) o Heavy load on server o Potential congestion on network o Presentation still tied to business logic 33 3-Tier Architecture o Each layer can potentially run on a different machine o Presentation, logic, data layers disconnected o Change in platform affects only the layer running on that particular platform 34 Client/Server Technologies 35 Types of servers ▰ Application Servers ▰ List Servers ▰ Audio/Video Servers ▰ Mail Servers ▰ Chat Servers ▰ News Servers ▰ Fax Servers ▰ Proxy Servers ▰ FTP Servers ▰ Telnet Servers ▰ Groupware Servers ▰ Web Servers ▰ IRC Servers ▰ Database Servers 36 Distributed Computing 37 Distributed Computing is a field of computer science that studied distributed system ▰ A distributed system is one in which components located at networked computers communicate and coordinate their actions only by passing messages. 38 Distributed Systems ▰ Distributed systems have autonomous components ▰ Distributed systems may be built using heterogeneous technology ▰ Distributed system components may be used exclusively ▰ Distributed systems are executed in concurrent processes ▰ Distributed systems have multiple points of failure 39 Centralized Systems ▰ Centralized systems have non- autonomous components ▰ Centralized systems are often build using homogeneous technology ▰ Multiple users share the resources of a centralized system at all times ▰ Centralized systems have a single point of control and of failure 40 Every application is part of a business model. ▰ They are developed using different platforms, OS and programming languages. ▰ must make them work together. 41 Middleware technologies enables the components to communicate to coordinate their activities. 42 Advantages of Distributed Systems ▰ Collaborative ▰ Expandability ▰ Local autonomy ▰ Improved performance ▰ Improved reliability and availability ▰ Potential cost reductions 43 Disadvantages of Distributed Systems ▰ Network reliance ▰ Complexities ▰ Security 44 Mobile and wireless computing 45 Mobile Computing ▰ Mobile computing is to describe technologies that ○ enable people to access network services anyplace, anytime, and anywhere, ○ with portable and wireless computing and communication devices. 46 ▰ Aspects of mobility ○ User mobility Between different geographical locations Between different networks Between different communication devices Between different applications ○ Device portability Between different geographical locations Between different networks 47 Applications of mobile computing ▰ Vehicles ○ transmission of news, road condition, weather, music via DAB ○ personal communication using GSM ○ position via GPS ○ local ad-hoc network with vehicles close-by to prevent accidents, guidance system, redundancy ○ vehicle data (e.g., from busses, high-speed trains) can be transmitted in advance for maintenance ▰ Medical ○ Nurses/Doctors in Medical offices are now using Wireless Tablet PCs/WLAN to collect and share patient information. 48 Applications of mobile computing ▰ Sales ○ Sales representatives are using Tablet PCs with Smart phones for presentation, transmitting/access information among office, hotel, and customer location. ▰ Emergencies ○ Early transmission of patient data to the hospital, current status, first diagnosis ○ Provide mobile infrastructure in dealing with Natural Disaster (earthquake, hurricane, fire), terrorist attacks, war,... ▰ Smart Environment ○ Smart home, Smart Car, Smart City 49 Challenges in mobile computing ▰ Mobility means changes ▰ Hardware ○ Lighter, smaller, energy management, user interface ▰ Low bandwidth, high bandwidth variability ○ Kbit/s to Mbit/s, bandwidth fluctuation ▰ Security risk ○ Devices more vulnerable, endpoint authentication harder ▰ Heterogeneous network ○ Different devices, interfaces and protocols 50 Challenges in mobile computing ▰ Location awareness ○ Locality adaptation ▰ Higher loss-rates, higher delays, more jitter ○ Connection setup time, hand-off ▰ Restrictive regulations of frequencies ○ Frequencies have to be coordinated 51 Wireless Network ▰ A wireless network allows devices to stay connected to the network but roam untethered to any wires. ▰ Access points amplify Wi-Fi signals, so a device can be far from a router but still be connected to the network. 52 Wireless Network Elements 53 Wireless Network Elements 54 Wireless Network Elements 55 Wireless Network Elements 56 Wireless Ad Hoc Network ▰ Wireless Ad Hoc Network (peer to peer) ○ A collection of autonomous nodes that communicate with each other by forming a multi-hop radio network in a decentralized manner. ○ No infrastructure, no default router available ○ “every” node needs to be a router ▰ Mobile Ad Hoc Networks (MANET) ○ Host movement frequent ○ Topology change frequent ▰ 57 Wireless Ad Hoc Network ▰ Wireless Ad Hoc Sensor Networks ○ A number of sensors spread across a geographical area. ○ Limited resources on sensors 58 Wireless Ad Hoc Network 59 Network Security 60 Network Security Key Elements ▰ Confidentiality ○ Preserving authorized restrictions on information access and disclosure, including means for protecting personal privacy and proprietary information. ▰ Integrity ○ Guarding against information modifications or destruction, including ensuring information non-repudiation and authenticity. ▰ Availability ○ Ensuring timely and reliable access to and use of information 61 Security Attacks, Mechanisms & Services Security Attack – Any action that compromises the security of information Security Mechanism – A process / device that is designed to detect, prevent or recover from a security attack. Security Service – A service intended to counter security attacks, typically by implementing one or more mechanisms. 62 Threats & Attacks … but threat and attack used nearly interchangeably 63 Security Threats / Attacks 64 65 Security Attacks classification ▰ passive attacks - eavesdropping on, or monitoring of, transmissions to: ○ obtain message contents, or ○ monitor traffic flows ▰ active attacks – modification of data stream to: ○ masquerade of one entity as some other: man-in-the-middle ○ replay previous messages ○ modify messages in transit ○ denial of service 66 Causes of network security threats ▰ Technology weaknesses ▰ Configuration weaknesses ▰ Policy weaknesses ▰ Human weaknesses 67 Networked multimedia system 68 Multimedia System ▰ Multimedia system is a computer (machine) that can transmit and accept information (multiple media) from the external world. ▰ supports the integrated storage, transmission and representation of the discrete media types text, graphics and image and the continuous media types audio and video on a digital computer. 69 Media types Text Hypertext Images Static & Dynamic Audio Speech, Music Video Movies, Documentaries 2D Graphics Vector Graphics 3D Graphics Games 70 Features of Multimedia System ▰ Very high processing power - In the modern multimedia context, movement and processing of large amounts of data in real-time are emphasized. - Include support hardware such as graphics and video adapters, digital signal processors and etc. ▰ A file system capable of handling multimedia information - File systems should have the capability to deal with streams of data, such as video and audio. 71 Features of Multimedia System ▰ File formats that exploit the inherent properties of the multimedia information - The file formats should be easy to handle from the file system point of view. ▰ Efficient and high I/O rate - The input and output subsystem should be able to handle large storage. - The controller hardware should be able to provide recording and reading of data from these storages. 72 Features of Multimedia System ▰ Storage and memory - Caches have to be larger and may have to be in a 2 or 3 level hierarchy for efficient management. ▰ Network support - To apply client-server paradigm in building multimedia application, high-speed support from the network subsystem is needed. - It should be able to stream the data out of the disk directly, to minimize delay. 73 Multimedia Applications ▰ Network application that transmit audio and video ▰ (“continuous media”) QoS network provides application with level of performance needed for application to function. 74 Classes of Multimedia Applications ▰ Streaming Stored Audio and Video ▰ Streaming Live Audio and Video ▰ Real-Time Interactive Audio and Video 75 Challenges ▰ TCP/UDP/IP suite provides best-effort, no guarantees on expectation or variance of packet delay ▰ Performance deteriorate if links are congested (transoceanic) ▰ Most router implementations use only First-Come- First-Serve (FCFS) packet processing and transmission scheduling 76 THANKS! 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